Arc lamp



A. J. HATCH Sept. 17, 1963 ARC LAMP 6 Sheets-Sheet 1 Filed F ns, 1959 f TIE-l- INVENTOR: ARTHUR J HATCH.

BY jAa/u Q Mug a4 ATTORNEY 6 Sheets-Sheet 3 30 M5 INVENTOR:

ARTHUR iHAmuz-r.

BY Wei ATTORNEY A. J. HATCH ARC LAMP Fri-4- Sept. 17, 1963 Filed Feb. 6, 1959 Sept. 17, 1963 A. J. HATCH ARC LAMP Filed Feb. 6, 1959 6 Sheets-Sheet 5 INVENTOR: ARTHUR L/THATEH.

ATTORNEY FIE-B- A. J. HATCH 3,104,066

ARC LAMP 6 Sheets-Sheet 6 Sept. 17, 1963 Filed Feb. 6, 1959 12.2mm 55x5 2.5:; w

. 3w wmw \Q; NM

INVENTOR ARTHUR JHATDH.

ATTORNEY United States Patent to The Strong Ohio, a corporation of This invention relates to are lamps and more particularly to are lamps embodying an air blown arc of comparatively short length and of high brilliancy especially adapted for use in motion picture projection, television casting and theater stage illumination and for other purposes where high intensity illumination is desired.

Arc lamps of this character have come into use to a certain extent for the above mentioned uses and purposes. In such lamps an air blast concentrically surrounds the arc discharge and is generally directed along the positive electrode toward the negative electrode so as to confine both the are discharge and the tail flame to a cylindrical region adjacent the tip of the positive electrode. In such lamps difficulties have been encountered in cooling the components of the supporting and driving means for the electrodes, in venting the lamps and in effectively conducting the gases and products of combustion away from the are without impairing the character of the arc.

The present invention relates to an improved lamp employing an air blown arc wherein the reflector, adjusting means for the reflector, the driving means for the. negative electrode and a gas exhaust duct for the blown are are supported upon a movable end closure or door of the lamp housing whereby improved operation of the lamp is attained.

Another object of the invention resides in the provision of a supporting head construction for the positive electrode of an air blown arc wherein the head construction embodies a semi-spherically shaped supplemental reflector means for utilizing or reflecting light rays from the are back through the arc to the main reflector which would otherwise be wasted as unreflected energy.

Another object of the invention is the provision of a supplemental reflector means associated with an electrode supporting head wherein the energy from the arc is reflected toward the arc and into the region of the air stream surrounding the electrode whereby the heat is more effectively withdrawn from the region of the arc.

Another object of the invention is the provision of a substantially universal mounting means for the main reflector of an arc lamp embodying a blown arc wherein the reflector is mounted upon a movable door or closure and adjustments of the reflector effected by control means exterior of the door.

Another object of the invention is the provision of a multiple air moving means supported by the lamp housing wherein one air moving means is effective to establish air pressure effective for directing air in the region of the arc and another air moving means effective to withdraw or exhaust the gases and volatile matter emanating from the arc and wherein both air moving means are driven from one motor.

Another object of the invention resides in an arrangement associated with a lamp housing and a movable door construction thereof of an air stream producing means and conveying ducts disposed so as not to impair the operation of the various components of the lamp structure and wherein ready access to the interior of the lamp housing is attained through a movable door construction which supports components of the air duct conveying means.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is a side elevational view of the arc lamp structure of the invention, certain parts being shown in section for purposes of illustration;

FIGURE 2 is a top plan View of the lamp structure shown in FIGURE 1;

FIGURE 3 is a rear view of the lamp construction with the end closure disposed in open position;

FIGURE 4 is a longitudinal sectional view through a portion of the lamp structure, the view being taken in the vertical plane of the electrode structures utilized for producing the arc;

FIGURE 5 is an elevational view of the interior of the door or end closure construction illustrating components carried thereby;

FIGURE 6 is a detail sectional view taken substantially on the line 6-6 of FIGURE 5;

FIGURE 7 is a detail sectional view taken substantially on the line 77 of FIGURE 5;

FIGURE 8 is an elevational view of an arrangement embodying light sensitive means for controlling the posi tion of the arc with respect to the reflector;

FIGURE 9 is a top plan view of the head construction supporting the positive electrode, and

FIGURE 10 is a schematic diagram of the circuits and electrical components of the lamp structure.

While the novel features of the improved arc lamp of the invention are illustrated as embodied in a lamp construction especially adapted for cinematography, television casting and illumination for theatrical purposes, it is to be understood that the features of the invention may be utilized in other forms of arc lamp construction such as search lights and the like.

Referring to the drawings with particular reference to FIGURES 1 through 3, the arc lamp construction of the invention is of a type embodying electrodes or carbons of the rod type, the lamp including automatic feeding means for the electrodes or carbons and for maintaining an are formed between adjacent tips of the electrodes in a focal position of a main reflector. The lamp structure includes a housing 10 which is generally cylindrical in shape and elongated in the direction of projection of reflected rays of light from the arc.

Mounted upon the upper portion of the housing 10 is a supplemental housing or casing 12 within which is disposed an air pressure producing means and an air suction blower which will be hereinafter described in further detail. The supplemental housing 12 is provided with a chimney or vent 14 for conveying away gases or products of combustion resulting from the oxidation of the electrodes during operation of the arc and for venting the housing 10. The supplemental housing 12 is provided with an opening 16 to admit atmospheric air into the interior of the supplemental housing.

The housing is equipped with a frontal frame member or closure 18 for the front end of the housing 10, the plate portion being provided with an opening through which is projected the light reflected from the arc. The rear end of the housing 10 is provided with a circularly shaped frame member 20 provided with projecting lugs or ears 21 to which is hinged a door or end closure 22 3 movable to open position for access to the interior of the lamp structure.

Latch means (not shown) is provided for securing the end closure or door 22 in closed position, the latch means being manipulatedby a handle 24 shown in FIG- URE 2. The housing includes a base'plate 30 having an upwardly extending portion 32 at one side which forms a support for an instrument panel 34 shown in FIGURE 1. A sheet metal panel 38 forming one lateral wall or side panel of the lamp ousing is secured to the front and rear frameslS and 20 by suitable means (not shown).

As shown in FIGURES 1 and 2, the side of the housing opposite the panel 38 is equipped with a panel 40 which is movably. supported for access to the interior of the housing. The front and rear frame members 18 and 20 are respectively provided with lugs or bosses 42. which are bored to receive a rod or shaft 44 extending lengthwise of the housing. The ends of the panel 40 are provided with members 46, the upper ends of the members being provided with openings through which extends the rod 44.

The rod 44 forms a pivotal axis for the movable panel 40. The lower ends of the members 46am provided with manipulating handles 43 for convenience in swinging the housing panel 49 upwardly to an 'open position. The movable panel 4% is provided with a Window 45 of tinted glass to facilitate visual inspection of the arc. The lamp construction includes a means for supporting a positive electrode 50 of the rod type and means for supporting a negative electrode 52 of the rod type which, during the operation of the lamp with an are formed between the tips of the electrodes, are in the position substantially as shown in FIGURE 4.

The positive electrode and the negative electrode are individually driven by separate electric motors controlled so as to advance the electrodes toward each other at substantially their respective burning rates supplemented by light sensitive cell means for controlling and maintain ing the gap between the electrodes where the arc is established at a predetermined focal region of a main reflector 54, the latter being arranged to project the light from the arc in a beam lengthwise of the housing through the aperture or opening 19 in the end frame member 18. i

The arrangement for supporting the positive electrode and the driving means therefor is illustrated in FIGURES 1, 3 and 4. As more especially shown in FIGURES 3 and 4, the bottom plate 30' of the lamp housing 10 supports a member 58 secured to the plate 30 by means (not shown) the member 58 being formed with an upwardly extending portion 60 defining a chamber enclosing components associated with the electrode 50, the portion 6t providing a support for the head construction surrounding the positive electrode.

Journally supported upon an upwardly extending pedestal portion 6% of the housing 60 is a pair of rollers 64 contained in a housing 66 as shown in FIGURES 4 and 9. The rollers 64 have peripheral grooves of semicircular cross-section adapted to engage diametrically opposite regions of the positive electrode and are rotated to advance the positive electrode Sit in a lefthand direction as viewed in FIGURE 4 ate rate to compensate for the burning away of the electrode. One of the rollers '64 is driven from a vertically disposed shaft 63, the lower end of the shaft being provided with a worm wheel '69 which is in mesh with a worm 70.

The shaft 68 driving one of the rollers 64 and a shaft 67 carrying the other roller are provided with meshing spur gears '71 to effect simultaneous rotation of both biases the housing in a direction to cause the rollers to frictionally grip the electrode 50*.

A projection or handle 75 extends from the housing 66 to facilitate manual pivotal movement of the housing to insert an electrode. The sides of the housing 6d are closed by means of removable closure plates 72 as shown in FIGURE 3.

The driving means for the worm 70 are illustrated in FIGURES 3, 8 and 9. The worm wheel 69 and the Worm 70 are journaled'within the housing 58.

The worm 70 is journaled upon a shaft 76 which is connected by means of universal joints 77, '78 and a connecting link or shaft '79 with a shaft 89 driven by suitable gearing contained in a housing 82., shown in FIG- URE 8. Thespeed reducing gearing contained within the portion 82 is driven from a suitable motor 84 and through this arrangement a drive is established from the motor 34 to the positive electrode Sll. The drive from the motor 34 to the universal joint 78 and shaft 80 is through a'friction disk clutch indicated at 86 in FIGURE 3.

This type of clutch is embodied in the drive arrangement for the positive electrode in order to facilitate a link or rod 89 with a control knob 99 disposed on rollers 64. The shaft 67 is journaled in the housing 66- the instrument panel 34 as shown'in FIGURE 1. By

.rotating the knob 9%), a manual drive to the shaft 68 is effected, the friction clutch 36 in the motor drive arrangement being of the friction type facilitating such manual adjustment.

The head construction surrounding the positive electrode is illustrated'in FIGURES 3, 4 and 9. The head construction is fashioned in two semicircular portions or components 92 and 94 which are mated or matched at a horizontal plane passing through the axis of the positive electrode 50 and are separable to admit insertion of a positive electrode or carbon. The head construction is inclusive of two semiannularly shaped members 95 and 96 which are of substantially identical construction.

The semiannular member 95 is mounted upon a semicircular backing plate 97 and the member 96 supported by a semicircular backing member 98-. The'mernber 98 is provided with a dependingportion 99 which 'is secured to a member 1% supported by the housing 6% and insulated therefrom by an insert fill of insulating material as shown in FIGURE 4.

Disposed within the semiannular members 92 and 94 are two semicircular cone-shaped members 104 and 106 which are formed with passage means for directing air under pressure along and surrounding the tip of the positive electrode and the are produced between the electrodes.

Each of the semicircular cone-shaped members 104 and 19 6 is formed with a manifold chamber 108 formed by a generally semicircular groove fashioned in each of the members, the groove being closed by a plate 110 welded to each member. As shown in FIGURES 3 and 4, a semicircular group of comparatively small passages 112 is formed in each of the members 134 and 1%, the passages being in communication withthe manifolds M8. The passages 112 are arranged at an angle to the axis of the positive electrode 50' as shown in FIGURE 4 in order to direct a plurality of streams of air under pressure toward a region surrounding the arc so as to confine and compact the arc and its tail flame at the tip of the positive electrode 50. V Y

Through this arrangement a stable blown arc is provided. The angularity of the air passages 112 may be modified depending upon the extent that it is desired to confine and concentrate the gases and tail flame of the arc.

The member 1% is fashioned with a manifold which receives air under pressure through a flexible tube 116 extending downwardly through the housing 6d. The manifold in the member 1% is in communication with the manifold MS in the lower member 106 through a passage 118 for supplying the lower semicircular manifold Hi8 with air under pressure.

The manifold in member 1% is connected by means of a flexible tube 12h with a fitting 12.2 which is in communication with a passageway .124 with the semicircular manifold 108 in the upper member 1% of the means for supplying air streams surrounding the are. The flexible tube 129 permits the upper head assembly 92 to be moved relative to the head assembly 4. The tube 116 is connected with a fitting 125 in the base portion 5%, the latter being connected by means of a flexible tube 126 shown in FIGURE 3 which is in communication with a source of air under pressure as hereinafter described. The head assembly is resiliently held in place by spring clips 12'] shown in FIGURES 3 and 9.

Means is provided for cooling the head assemblies 92 and 94. As shown in FIGURE 4, the upper member 97 is formed with a semiannular channel or duct 13% and the lower member 99 formed with a similar duct 132. The ducts 130 and 132 are adapted to receive a circulating cooling fluid such as water. Extending upwardly through the housing 69 are water supply and return tubes or pipes 134 and 136, the pipe 134 being in communication with the semiannular channel 132 in the lower member 98. The channel 132 is in communication with the channel 13% by means of a flexible tube 138.

The channel 130 in the upper member 97 is connected with the return tube 136 by means of a flexible tube Mt) shown in FIGURE 4. The inlet tube 134- is connected with a water supply tube 142 shown in FIGURE 3 extending through the member 58 and the return tube 136 connected with a tube 143 also extending through member 58. The inlet tube 142 is connected with a water flow control switch 27% shown in FIGURE 5. The water may be supplied from a pressure source and the spent water delivered into a waste sump or the water may be directed through a cooling system and a recirculator for reuse.

Each of the semiannular members 94 and 95 is formed with a semispherically shaped reflecting surface 146, each surface being generated as a radius with the central region of the are as a center. The two semispherically shaped surfaces 14 6 together form a supplemental or auxiliary spherical reflector adapted to reflect light rays from the are, which would otherwise be unreflected, back through the arc and onto the main reflector 54.

The supplemental reflector provided by the surfaces 146 serves dual purposes, it reflects the light, which would normally be unreflected, back through the arc and onto the main reflector whereby substantially all of the light rays from the are are projected from the main reflector 5'4 as the projected light beam and also reflects heat back through the are so that more of the heat generated by the arc is carried away by the air streams flowing through the passages 112 and the means for exhausting the gases hereinafter described.

It has been found that a more stable are may be obtained by flowing the arc current for the positive electrode 50 around the electrode prior to delivery of current to the electrode to establish a magnetic field surrounding the arc. As shown in FIGURE 4 the semiannularly shaped members 95 and 96 are formed with a circumferential groove or recess M8 to accommodate two convolutions or turns of the current conductor or lead for the positive electrode 50. The end of the conductor is secured to member 98 by means of a securing bolt 152.

The member 98 is provided with silver contacts (not shown) which engage the electrode 50 to conduct current thereto. The opposite end of the conductor 15%) is secured to a terminal post 154 which is insulatingly supported by a block 156 carried by the housing 60. Current is supplied for the are through a lead 158 connected to the terminal post 154. The control means for the motors operating the positive electrode and the negative electrode will be hereinafter described. The coolant circulating tubes 134, E36 and the air supply tube 116 are suitably insulated from the member 58 and the up wardly extending housing 69.

The arrangement includes a novel support and driving means for the negative electrode 52. As shown in FIG- URE 4, the negative electrode supporting and driving means is inclusive of a member 162 upon which is mounted an electrically energizable motor 164 for feeding or advancing the negative electrode. The member 162 and associated components for supporting and driving the negative electrode are carried by the hinged door or end closure 22. of the lamp structure. As shown in FIGURE 5, the support member 162 is formed with transversely spaced upwardly projecting portions 166.

Extending through openings formed in portions 166 are transversely extending rods or members 168 and 170. Pivotally supported upon the upper rod 168 is a bracket 178 formed with upwardly extending spaced portions 180 shown in FIGURE 5. Secured to the rod 168 is a worm gear 172. which is in mesh with a worm wheel 174 carried by a member 176. A tenon portion of member 176 extends into a bore in an element 182 which is journally mounted in a bracket or member 184, the member 184 and 1S2 being supported by the member 178.

The member 178 is formed with a forwardly extending portion The provided with a bearing 188 of a type to accommodate limited angular movement of a shaft 194 extending through the hearing. The member 184 is provided with boss portions 1% and 192, the boss 192 containing a journal bearing for the shaft 194. Mounted upon the rod or shaft 194 is a driven worm wheel 196 having a hub portion 198 journaled in a bore formed in the boss portion 1%.

The rod 194 extends through the gear 196 and hub 198 and is splined thereto whereby rotation of the gear 1% rotates the rod 194, the splined connection permitting longitudinal slidable movement of the rod 194 with respect to the gear 196. The forward extremity of rod 194 is equipped with a drive roller 2% for the negative electrode 52. The roller 200 has a series of spiral grooves 011 the periphery which during rotation of the roller 2% engage the negative electrode 52 to advance the negative electrode as the tip thereof is burned away.

The opposite end region of the rod 1% is equipped with a head portion 204, an expensive coil spring 206 surrounding the rod and being disposed between the gear 196 and the head portion 204 to resiliently bias the rod in a lefthand direction as viewed in FIGURE 4. Mounted upon the shaft is a block 208 which is threaded onto a threaded portion of the shaft 170. The block 208 is of a lateral dimension to extend between depending portions 21! formed on the bracket 178 whereby the projections straddle the block 208.

As the block 298 is threadedly mounted upon the shaft 171., rotation of the shaft 170 moves the block lengthwise of the shaft and, through its engagement with the depending portions 21ti, moves the electrode supporting bracket 17% in a transverse direction in order to secure proper alignment of the negative electrode 52 with the positive electrode in a vertical plane. After this adjustment has been made the shaft may be locked in position by a nut 212.

The means 184 supporting the electrode driving shaft 194 is adapted to be adjusted in angular directions about the bearing 1% by means of the pin 176 eccentrically positioned in and secured to the circular member or trunnion 182. By changing the angle of the axis of rotation of the drive roller 2%, the rate of feed or advancing moveenoaoee ment of the negative electrode may be regulated at the rate at which it is burned away.

A change in angularity of the axis of roller 2% is attained by rotating the shaft 168 and worm 172, the latter driving the worm wheel 174 and, through the medium of the eccentricity of pin 176 with respect to member 132, the member 182 is rotated to shift the position of the bracket 184 about the center of the bearing 188 supporting the rod 194 adjacent the drive roller 2%.

Secured to, the projections 21d is a plate 216, the lower end of which is provided with an opening to receive a threaded bolt 218, the head of the bolt being in engagement with the plate 216. The bolt 218 extends through an opening in a vertical Wall portion 163 of the member 162. An expansive coil spring 229 surrounds the bolt 218 and is disposed between the wall portion 1% and the plate 216 to resiliently maintain the bracket 186 in a predetermined position.

By adjusting the position of the bolt 218 by means of a suitable tool inserted in an opening 222 in the end closure 22, the bolt may be rotated so as to adjust the bracket 178 about the axis of shaft 162 to change the angle of inclination of the negative electrode 52 in a vertical plane so as to properly position the tip of the negative electrode slightly below the axis of the positive electrode as shown in FIGURE 4-.

This adjustment is important in that the gases and volatiles from the arc and the :air of the streams confining the arc are drawn through an exhaust opening disposed above the negative electrode while maintaining the arc substantially on the axis of the positive electrode at the focal point of the main reflector 54. The drive roller 2% is rotated by the electrically energizable motor 164 through speed reducing gearing contained within the hollow base portion of the member 162.

The gearing rotates a shaft 224 which, through the medium of universal joints 2% and a link or rod 223, drives the shaft 230 which is journaled for rotation in the member 184. The upper end of the shaft 230 is provided with a worm 232 in mesh with the worm wheel 1%, the latter being driven thereby to impart rotation to the roller 2%.

The arrangement illustrated includesa manually actuable means for initially striking the are by moving the negative electrode 52 into contact with the extremity of the positive electrode 56.

The upwardly extending portions 1% of the member 178 support a shaft 234 upon which is fixedly secured a are and the gases and volatiles resulting from the burn- 'ing of the carbon electrodes. As shown in FEGURE l, a

depending member 236 of generally U-shaped configuration, the bight portion being disposed adjacent the head 2% formed on the end of shaft 194. The shaft 234 is connected through the medium of universal joints 2% with an actuating member or handle 241i shown in FIGURES l and 2 disposed exteriorly of the end closure 22 for convenience of operation by the operator.

I When it is desired to strike the arc, the operator moves the actuating handle .240 to rotate the shaft 234 in a counterclockwise direction as viewed in FIGURE 4, this action causing the portion 236 to move the head 2% and shaft 1% in a right hand direction as viewed in FIGURE 4, compressing the spring 2%. As the roller 2% is in engagement with the electrode 52; the forward movementof the roller 200 carries the electrode 52 therewith, bringing the tip of the negative electrode into engagement with the crater end of the positive electrode.

This engagement completes the circuit through the electrodes to strike the arc. When the engagement has been made and the arc formed, the operator releases his grasp from the handle 24% and the expansive spring 206 retracts the rod 194and the drive roller 2% to their normal electrode driving positions.

The arrangement of lamp construction of the invention includes a novel means for delivering air under presand for exhausting and venting the air blown around the plate 242 forms a roof for the lamp housing 1t and supports a bracket 244 upon which is mounted an electrically energizable motor 2 36.

Supported at one end of the bracket 244*- is a generally circular blower housing 248 in which an impeller, air moving means or rotor 249 is disposed which is carried or mounted upon one end of the motor shaft The blower housing 248 is fashioned with an air outlet 252 which extends into the venting chimney 14. Supported at the opposite end of the bracket 244 is a second blower housing 254 in which is disposed an impeller, rotor or air moving means 255 mounted upon the opposite end of the motor shaft 251) which extends into the blower housing 254. V V

Thesecond blower 25 is provided with a cylindrically shaped member 256 defining an air entrance chamber which is open to the interior of the casing 12 and adapted to conduct air entering the housing opening 16 into the blower housing 254 under the influence of the suction produced by the impeller in the housing 25 3 to develop a source of air under pressure. a I

Disposed beneath the plate 2 52 is a sheet metal casing 258 forming a chamber which receives air under pressure established by rotation of the rotor 255 from the blow r housing 254 by means of a duct 260. The air duct or tube 126 connects the chamber provided by the casing 258 with the lower portion of the support 58.

in this manner air under pressure contained in the chamber formed by member is conducted by the tube 126 to the positive electrode supporting means provi'ding the pressure air to the passages 112 directing the air around the are formed between the electrodes.

Mounted upon the cylindrical extension 256 forming the air entrance into the blower housing 254 is a switch means contained in housing 2-64 which is equipped with a swing-able vane 26o disposed in the chamber or passage provided by the member 256. The switch 264 is conected by leads contained within a sheath 268 with a water circulating control switch 27% shown in PE- URE 5.

The switch mechanism contained in the member 264 is actuated or controlled by movement of the vane ass, and his switch means is in series with the water circulating control switch 276 and with a power switch '(not shown) whereby a circuit through the electrodes cannot be completed until the blower motor 246 is energized to establish air under pressure in the chamber for delivery from the passages 112 around the positive electrode and cooling water or other coolant circulating through the cooling system from a water supply or water circulator through the Water interlock switch 27%.

The exhaust or "ent system for carrying away the air from the blown arc and the gases and volatiles resulting from combustion of the electrode material is more par ticularly shown in FIGURES 1, 4 and 5.

Disposed at the forward region of the negative elec trode 52 is a hollowmemberZM- which is secured to a tubular elbow shaped member 276. As shown in PP- URE 1, the upper portion of the door or closure 22 is formed with a chamber 2T8, the lower wall 231} of the chamber being provided with an opening to receive a equipped with a silver contact means 292; which engages I 9 the periphery of the negative electrode 52 to establish a current supply thereto and a heat guard plate 2%.

The contact 292 is connected by means of a lead wire 294 shown in FIGURE for supplying current to the negative electrode. The member 274 is arranged to be cooled by circulating coolant fluid such as water. The wall structure of member 274 is provided with a chamber 2% in communication with a Water inlet tube 2% shown in IGURE 5. The chamber 2% is provided with an outlet tube 300 shown in FIGURE 5 which is connected with the Water control switch 27d.

The water control switch 274? is connected by means of a tube 142 shown in FIGURE 3 with the water circulating system for the head surrounding the positive electrode, the outlet tube for the latter system being shown at i 53 in FIGURE 3. The outlet tube may be connected with a recirculator (not shown) if the water is to be cooled and recirculated or conducted to a waste sump.

The path of the cooling fluid or water is as follows: The water is supplied by the inlet tube 2% shown in FIGURE 5 to the chamber 2% adjacent the negative electrode vent means 274- from a suitable water supply or from a recirculator. The water flows through the chamber 2% to cool the member 274, the water from the chamber 296 flowing through the tube see through the water control switch 276 thence through the tube 1 3?. and through the tube system for supplying circulating water through the channels 130 and 132 in the head members 97 and 98 adjacent the positive electrode 59, the water then being returned to a water circulator or disposed as waste through the tube 143.

Thus it will be seen that the water, after flowing through the chamber 2% adjacent the negative electrode, is conducted to the positive head for controlling the temperature of the head construction. The water control switch 270 is in circuit with the switch means associated with the swingable vane are and connected through a relay (not shown) associated with the arc current supply so that current will not flow through the electrode until the circulation of water has begun and the motor 245 driving the exhaust blower and air pressure systems has been energized.

It will be seen from FIGURE 1 that the supporting and driving means for the negative electrode, the venting members 274 and 276, the flexible tube 283 are carried upon the hinged door construction 22. When the door is in closed position, the opening registers with the entrance in the elbow portion 286 so as to establish a continuity of reduced pressure or suction effective at the entrance of the member 274 through the operation of the impeller contained in the suction blower housing 242%.

The members 274 and 276 are preferably formed as castings and have substantial weight and through the provision of the flexible tube 283 the weight is effective to hold the silver contact 292 in engagement with the negative electrode 52.. Spring means 392 may also be utilized to augment the downward pressure of members 274 and 276 to maintain the contact 292-111 current conducting engagement with the negative electrode 52.

The lamp construction of the invention includes a novel means for varying the motor speed for feeding the positive carbon so as to maintain the are at a predetermined focal point with respect to the reflector 5d. Disposed interiorly of the housing all of the lamp construct-ion is a tubular member 38 3 extending longitudinally of the housing as shown in FIGURE 8. Arranged within and at one end of the housing is a member 3% supporting a prism 3% of the total reflecting type.

Disposed at the opposite end of the tubular member 3% is a selenium cell or current producing light sensitive means contained within a housing 312, the cell being schematically illustrated in FIGURE l0.

As shown in FIGURE 4, the lower semiann-ular member as of the positive head construction is provided with a notch 311 to permit the transverse beam of light from to the arc to be received by the prism 3% and reflected by the prism onto the solar cell or light sensitive cell in the housing 312. Further operation of the control means contained in housing 312 will be described in connection with the circuits illustrated in FIGURE 10.

The reflector 54 is mounted upon the movable door or closure 22 in a manner whereby the same may be adjusted axially of the positive electrode and tilted angularly to establish the proper correlation of the reflecting surface and the arc. With particular reference to FIG- URES 4 and 5, there is disposed adjacent and rearwardly of the reflector 54- a supporting ring or annulus 304.

The ring 364 is provided with four removable cleats 395, each cleat being formed with a recess 307 which receives the peripheral edge region of the reflector as shown in FIGURES 6 and 7. Each of the cleats M35 is secured to the ring by means of winged bolts 31%. The ring sea is supported by adjustable means carried by the closure or door 22. The metal door structure 22 is provided with two pairs of bushings 313 and 314- secured in bores formed in the door structure, one of each pair being shown in FIGURES 6 and 7, which are arranged in circumferentially spaced relation in intersecting planes.

The bushings 313 receive threaded shafts 316 and the bushings 314 receive threaded shafts 31%, one of each being shown in FIGURES 6 and 7. The ring 3&4 is formed with pairs of lugs 32% and 322 adjacent each of the reflector securing cleats 3G5 and each is provided with a threaded bore to receive the winged bolts 310.

Each of the lugs and 322 is formed with a cam surface 324. Mounted upon the distal end of each of the shafts 316 is a member 32 5, each member journally supporting a cam roller or follower 328.

Each of the members see is provided with a threaded opening receiving the threaded portion of a control rod 33% which extends exteriorly of the door 22 through an aperture in which it is slidably received and is provided with a manipulating knob or grip member 332;. The opposite end of each of the rods extends through an opening in a bushing 33 lcarried by the supporting annulus Mounted on each of the shafts 316 is a U-shaped member 336 secured to the adjacent bushing 313 and which straddles a toothed sprocket 333 threaded on the shaft 316.

A pin 34 19 is carried by each of the members 326 and extends through a bore formed in the bight portion of member 336 to prevent relative rotation thereof. With particular reference to FIGURE 7, it will be seen that the shaft 313 is connected with a member 342 formed with an opening to accommodate a shaft 344, one end of which extends into an opening formed in the door 22, the other end extending into an opening formed in the ring C's-dd, the member 342. being adapted for slidable movement along the shaft Secured to the ring adjacent each of the rods 344 is a bracket 346 having s depending portion 348 provided with an opening accommodating the shaft or rod 344. An expansive coil spring 35f surrounds the rod between the portion and the member 342 which provices a resilient means accommodating tilting adjustments of the reflector as hereinafter explained. Each of the shafts 318, like the shafts 316, is threaded through a toothed sprocket 352.

A U-shaped member 354, of the same shape as memers 336, is secured to the adjacent bushing 314 and straddles each sprocket 352, the shaft 318 extending through the U-shaped member 354. A pin 356 carried by each of the members 342 extends through a bore in the bight portion of each of members 354 to prevent relative rotation thereof. The pairs of sprockets 33S and 3-5-2 are arranged as shown in FIGURE 5 at equal distances oircurnferentially of the annulus 394 and equal distances from the axis of the reflector.

A chain 36d takes over each of the sprockets 338 and 352. and over a sprocket 36?; journaled upon a boss portion 364 formed on the door or closure 22;. A shaft 365 supporting the sprocket is provided with a manipulating member see extending exteriorly of the door, the rotation of the sprocket by manipulating the knob are causing rotation of all of the sprockets simultaneously. As the sprockets are threaded on the threaded shafts 31d and Sid, simultaneous rotation advances or retracts the reflector supporting ring 3% and the reflector 54 taxi-ally and in a direction dependent upon the rotation of the actuating sprocket 362.

An idler sprocket 368 is mounted upon an adjustable bracket 376 and engages sprocket chain are to eliminate lost motion of the chain. The control shafts 330 may be individually rotated by their respective knobs 332 to secure a tilting of the reflector in any angular direction. By rotating a knob 332,-the member are associated therewith is threaded along the rod to change the position of the roller 32-8 wheich cooperates with the cam surface 324 of 9. lug 32% to effect a tilting of the reflector in one plane.

When the knob 332 of the other shaft 5% is rotated, the member are associated therewith is moved to effect a tilting of the reflector in a plane at 90 to the first mentioned plane through a change in the relative position of the cam roller 328 cooperating with the cam surface 324 of the adjacent lug 3255. By manipulation of the control knobs 332 the reflector may be til-ted at any angle Within the range of movement of the members 326 and 342.

From the foregoing, it will be seen that the reflector 54 may be adjusted fore and aft along its axis by simultaneous rotation of the sprockets through the control knob 366 and may be adjusted angul-arly by individual adjustment of the cnn-trol knobs 332 for moving the members 326.

FIGURE illustrates schematically the circuits for the electrodes and control components therefor. The current supply leads 372 and 373 are connected with a generator or rectifier providing a source of direct current. The lead 373 is connected to the positive electrode 58, the portion b of the lead 3-73 extendingaround the positive electrode as shown in FIGURE 3 to establish a magnetic field around the positive electrode so as to lend stability to the arc. 'The lead or conductor 373 is flexible and loosely surrounds the head to accommodate limited separation of the semicircular head components {for the insertion of electrodes.

The lead 372 is connected through an ant-meter 37 i and to an arc control relay 375. The lead 372 includes a current coil 3'76 surrounding the core 377 of the relay 3:75,- the coil being connected by lead or conductor 2% to the negative electrode 52 through the connection with the contact 2% associated with the arcyenting member 274 shown in FIGURE 4. The feed motor for the positive electrode is indicated at 84 land the feed motor for the negative electrode is indicated at 164.

The control means includes an arc current selector rheostat 386 Which is mechanically connected with a rheostat 382 for adjusting the feed of the positive electrode. The movable arms 3&1 and 3% of the rheostats 38d and 382 are mounted upon the same shaft whereby both rheostats are adjusted simultaneou ly. The shaft extends through the instrument panel 34- and is provided with a control member 334 shown in FIGURE 1.

Also mounted upon the instrument panel 34 is a manipuiating member 386 .for controlling the power for are are circuit 372 and 373 where a controllable rectifier or generator is employed as a power source. The field 388 of the positive electrode feed motor 84 is connected through the feed rheostat 332 with a relay 392. The relay 392 is of the swinging armature or arm type and is associated With a resistance 3% for modifying the strength of the field 383 to change the rate of rotation it; of the armature 395 of the motor 84 and thereby change the rate of feed of the positive electrode.

The selenium cell control means 312 Which is activated by a beam of light from the arc reflected by the prism 368 onto the selenium cell 333 in the unit 312. The housing or" the unit 312 isprovided With a slit or opening 315 to admit projection of light energy upon the selenium cell. The light energy impressed on the cell 313 generates a current which is amplified by a transistor amplifier contained in the unit 312 and the amplified current conducted to a coil 394 in the relay 392. 7 7

Under the influence of a reduction or cessation of current in the coil 3%, which ensues when the arc is in an improper position and the light is deflected away from the slit 315 and the selenium cell, the relay 392 functions to modify the strength of the field 38d of the motor 84 and thus varies the speed of advancement of the positive electrode. i

The arrangement includes a voltage divider resistor 4%. The portion 162 of the resistor 4% is shunted across the armature of the negative electrode feed motor 164. The portion 4% of the resistor 4% and the resistance 4% are controlled by a relay 416*! in a manner hereinafter described. An indicator light 412; is provided in the field circuit of the negative electrode feed motor 164. A portion 414 of the voltage divider resistor 4% is shunted across the armature 395 of the positive electrode feed motor 84.

- The portion ilt; of the resistor dill) is, at times, taken out of the circuit by the relay An indicator light 4-17 is in circuit With the relay 392. for indicating the condition of the relay 3% in controlling the speed of the positive electrode teed motor 84. The relay 375 is provided with a movable armature 42% which is connected with the arc current lead Wire 294 by means of a lead 421. 7 under the influence of a spring 422.

A lead or conductor 424, provided with a contact 426 adapted to be engaged by the armature 42%, is connected with an energizing coil 47.8 of the relay are which is effective to change the speed of rotation of the negative electrode teed motor as hereinafter explained. A resistance $32 is shunted across the armature 420 and the stationary contact 426 to reduce arcing at the contacts.

A second coil 436 is mounted on the relay core 377 which is in series with the adjustable arm 381 of the arc current selector rheostat 38%) whereby the rheostat 38d and the coil tea are shunted across the arc current conductor 294 through the leads 44-0 and 442. This shunt circuit Which includes the rheostat 38d and coil 436 is of low current carrying capacity and is utilized to control, within limits, the "amount of current flowing through the current conductor 294 of the are circuit.

The movable or sWinga-ble arm of the relay 431i is indicated at 446 and cooperates with contacts 447 and 448. The relay 4-H is of sensitive character, the armature 446 being movable from one contact to the other under the influenceof our-rent flow in the energizing coil 42% whereby the relay 4% is effective to vary the speed of the armature 41;]. of the negative feed motor 164 in accordance with variations of current in the arc circuit which afiect the position of the armature 42d of the arc control relay 375.

The swingable armature or arm of the relay 392 is indicated at 452 and cooperates with contacts 53 and 454 I to change the speed of the armature 395 of the positive feed motor he as influenced by the position of the light beam from the arc with respect to the selenium element 313 in the control unit 312.

The casing of the selenium cell unit 312. is provided With a narrow slit 315, indicated in FIGURE 10, through which the beam of light L from the are projected by prism 3 .33 is eiiective to generate current by reason of the light energy, which biases a transistor amplifier in the unit 312 and reduces the current in the coil 3% of the relay 392.

When the arc position changes by reason of a feed The armature 42-3 is. biased in one direction! motor of the positive electrode 50 moving at a rate greater than its burning rate, the projected beam of light is deflected away from the slit 315 causing a decrease or cessation of current flow through the coil 394 resulting in a movement of the armature or arm 452 to engage the contact 454 and shunt out the resistance 3% in the circuit of the field 388 of the positive electrode feed motor 84. This action reduces the speed of the motor 84.

Prior to the operation of the lamp, the negative electrode must be adjusted and positioned to establish a proper correlation with the crater end of the positive electrode. The angularity of the negative electrode is adjusted by the operator by manipulating the bolt 218 to tilt the negative electrode supporting structure about the axis of the shaft 168' so as to position the tip of the negative electrode 52 slightly below the axis of the positive electrode 5% in alignment with the lower edge of the crater of the electrode Si).

This position is essential so that the negative electrode presents a minimum of obstruction or impediment to the formation of the blown arc. By establishing this position for the tip of the negative electrode, a cylindrically-shaped blown arc of smooth exterior contour is provided under the influence of the air streams projected through the passages 112 in the positive head and the suction or reduced pressure effective at the venting means.

The angularity of the shaft or rod 194- carrying the feed roller 200 is adjusted in a lateral direction by rotating the shaft 168 which causes rotation of the worm 172, worm wheel 174 and member or trunion 182 to swing the driving roll supporting rod 194 about the center of the bearing 188 to adjust the angularity of engagement of the spiral or askew ridges formed on the drive roller 200 with the electrode 52 to regulate the rate of feed for the negative electrode toward the arc to compensate for the burning away of the material of the electrode during operation of the lamp.

The operator adjusts the lateral position of the negative electrode support with respect to a vertical plane through the axis of the positive electrode 52 by rotating the shaft 170, and through the threaded connection between the block 208 and the shaft 170, the electrode support may be moved laterally to position the tip of the negative electrode in a vertical plane through the axis of the positive electrode.

The operation of the lamp is as follows: The motor 246 arranged to drive the impeller of the exhaust blower 248 and the impeller of the air pressure producing means 254 is started by closing a suitable switch (not shown) to energize the motor from a conventional alternating current power source. A recirculator (not shown) [for cooling water is brought into operation or the water inlet tube 298 connected with a conventional water supply under pressure.

The switch means in the member 264 is actuated by swinging movement of the vane 266 caused by air flow through the air entrance 256 to the blower 254 when the motor 246 is started. The blower 254 delivers air under pressure to the passages 112 to provide air for the blown arc. The suction blower 248 establishes sub-atmospheric pressure or suction in the venting means 274 adjacent the negative electrode 52 to exhaust gases from the arc.

The water interlock or control switch 270 of the pressure type is closed automatically when water pressure is impressed in the water circulating system of the lamp. After the motor 246 has been started, the operator closes a power switch (not shown) to initiate current flow to the arc circuit leads 372 and 373 from a power source such as a direct current generator or rectifier. However current does not flow through this circuit until the arc is struck or established. During starting and operation of the lamp the end closure or hinged door 22 is in closed position as shown in FIGURE 1.

The operator establishes or strikes the are by moving the manipulating handle 240 which rotates the shaft 234 causing the depending U-shaped member 236 to engage the head 204 on the shaft 194 to move the shaft carrying the drive roller 2% in a forward direction. ridges formed on the drive roller 200 engaging the negative electrode 52, the negative electrode is advanced until its tip engages the lower edge of the crater of the positive electrode 50 to complete the circuit through the are provided by the leads 372, 373 and the connection 2% thereby striking the arc.

The operator adjusts the arm 438 of the arc current selector rheostat arm 380 which through the mechanical connection also adjusts the feed rheostat 382 for varying the effectiveness of the field of the positive feed motor 84 to increase or decrease the speed of the motor 84-. The resistance provided by the rheostat 380, in circuit with the coil 436 of the arc control relay 375, is effective to obtain limited control over the current flowing through the positive electrode supply lead 294.

By inserting more resistance of the rheostat 330 in the circuit with the coil 436 a lesser amount of current flows through the coil 436 and a greater amount of current flows through the current coil 376 and lead 294 to the negative electrode.

The are control relay 375 cooperates with the swing relay 410 for controlling the negative electrode feed motor 164 in the following manner:

The rheostat 38% is set to the approximate burning rate desired for the positive electrode. The relay 375 is eifective to automatically maintain the proper feed of the negative electrode. When the arc current increases, it establishes an unbalanced condition in the relay 3'75 causing the armature 4 20 to engage the contact 426 energizing coil 428 of the relay 416.

The relay arm 446 swings into engagement with the contact 448 to shunt out the resistance 4% in the field circuit of the negative electrode feed motor 164 causing the armature thereof to rotate at a slower speed and thus reduce the rate of advancement of the negative electrode 52.

The slowing down of the rate of advancement of the negative electrode affects current in the conductor 294 and coil 376 causing the armature 420 of relay 375, under the influence of spring 422 to be disengaged from contact 426, deenergizing the coil 428 in relay 410.

This action causes the armature 446 to reengage contact 447, reinserting the resistance 4% in the field circuit of motor 164 whereby the armature of motor 164 is ro tated at its higher speed to advance the negative electrode 52 at an increased speed. The indicator light 412 is arranged in the field circuit of motor 164 and is adapted to be energized when the resistance 406 is shunted by the relay did.

It is to be understood that during operation of the lamp there is a continuous cycling of operation of the relays 375 and 416 in order to maintain the feed of the negative electrode 52 at a proper rate in accordance with the current selected by the arc current selector rheostat 380.

The automatic control of the feed rate of the positive electrode functions as follows: When the arc is in the proper position, the beam of light reflected by the prism 368 is aligned with the slit 315 in the selenium cell 313. The impression of the light energy on the solar cell or unit 313 generates a current which biases the transistor amplifier in the housing 312, reducing the current through the coil 394 of the relay 392.

The current value flowing through the coil 394 is substantially constant while the light energy passes through the slit 315 to activate or energize the cell 313. In this condition, the arm or armature 452 of relay 392 is maintained in the position shown in FIGURE 10 is engagement with contact 453 which places the resistance 3% in circuit with the positive electrode feed rheostat 332 and the field 388 of the positive electrode feed motor 84 to maintain a predetermined feed rate for the positive electrode 5t).

Due to the e that tie lamp is operating propenly.

alliance iii If the positive electrode fill advances at a greater rate than its burning rate, the position of the arc is changed so that the beam of light projected by prism 3% is defiected from the slit 315 and from the selenium cell 313. This action causes a reduction or cessation of current produced by the cell 313 so that the current is reduced in the coil 3% of relay 3%.

This condition causes the armature 452 of the relay. 3?? to engage the contact shunting out the resistance 3% and thus reducing the speed of the armature of the positive electrode feed motor 84 to reduce the rate of advancement of the positive electrode i). By slowing up the feed rate of positive electrode 5d, the arc is reestablished at its proper position, the light beam projected from prism is realigned with the slit 315 to energize the selenium cell 316 and reestablish predetermined current flow in the coil 3%.

- This causes the armature 4-52 of the relay 392 to be moved to the position shown in FEGURE 1G, reinserting the resistance 3% in the circuit of the field 383 of the positive electrode feed motor 84 to cause the motor to rotate at its predetermined higher speed.

The above described operations of the relay 392 occur intermittently or in cycles so as to maintain the are at its proper position with respect to the curvature of the main reflector 54.

The indicator light 417 associated with the relay 392 is adapted to be energized when the relay is in a position to effect the higher motor speed of the positive electrode feed motor The values of the resistances 4492, 4%, 414 and 416 are established to obtain most eifi'cient operation of the electrode feed motors 84 and 11:54. The relays 375, 392 and are are comparatively sensitive to small current variations so that minute variations in current in the coils of theserclays are effective to move the'armatures or arms of the relays for controlling the speed of the electrode iced motors in the manner above described.

While the arc current and voltage of different values :may be employed in the lamp of the present invention, it is found that a high efficiency of illumination and brilliancy of the arc are obtained at voltages of from 6 5 to 76 volts and an arc current of from 120 to 155 amperes. The power source for the lamp may be a genorator designed to deliver direct current or a suitable rectifier for converting alternating current to direct current. If the electrodes constantly overfeed or the arc gap becomes too short, then the power to the arc is too low for the burning rate selected and power to the electrodes must be increased. If the carbons underfieed constantly or the arc gap becomes too long, the power to the arc is too high for the burning rate selected and the power must be decreased.

The cycling of the control relays causes intermittent energization and flashing of the indicator lights 412 and 417. This intermittent flashing informs the operator If one of the indicator lights remains on or off for a substantial period of time, the operator is thus visually advised that the lamp is not operating properly and requires adjustment or that the electrodes have been consumed and require replacement.

It is apparent that, within the scope of the invention, modifications and diiferent arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim: i

1. In combination, an arc lamp having a housing, a

pair of electrodes in said housing disposed to produce said cam followers cooperate with the adjacent cam surfaces to tilt the reflect-or.

2. in combination, on are lamp having a housing, a pair of electrodes in said housing disposed to produce an arc, a hingedly supported end closure mounted on said housing, a relleotor arranged to project light rays from the are, means carried by said end closure for supporting said reflector, said reflector supporting means including an annular member, a plurality of cleats removably carried by'said annular member and engaging said reflector for sec-urintg'tihe reflector to the annular memher, a plurality of elements adjustably supported by said end closure, said elements having operative connection with said annular member, a plurality of sprockets, each or said sprockets being operatively connected with one of said elements, a chain engaging said sprockets, means for moving said chain to simultaneously actuate said sprockets and elements for adjusting said reflector length wise of its axis, and manually operable means individual to and connected with certain of said elements for selectively adjusting the same to ellect tilting movements of too reflector.

3. in combination, an arc lamp having a housing provided with a base plate, a relatively movable end closure carried by said housing, positive and negative electrodes in said housing disposed to produce an are, a reflector supported by said end closure a-rranged to projec light from the arc, means mounted on said base plate adapted to support the positive electrode, a member sumounding the positive electrode having orifice means arranged to d" ct a hollow column of air under pressure toward the arc for confining the arc, means mounted on said end closure and movable therewith support- :ig said negative elec de, a first motor mounted by the housing for advanc i g the positive electrode, a second motor supported by the end closure for advancing the negative electrode, said motors being adapted to advance the electrodes toward each other in proportion to their respective burning rates \to maintain the arc in a substantially constant position, vent means carried by the end closure disposed adjacent saidncigative electrode supported by and movable with said end closure, a suction blower and an air pressure producing means mounted by said housing, a third motor mounted on the housing adapted to drive said suction blower and said air pressure producing means simultaneously, tubular passages provided in said housing and end closure in communication respectively with said suction blower and said vent means, said tubular passages being arranged for registration when said end closure is in closed positi-on whereby to exhaust the gases of combustion (from the arc and the air Oil the hollow column surrounding the arc, and passage means in said housing lor conveying air from the air pressure producing means to the orificed member surrounding the positive electrode to provide the hollow column of air.

4. ln combination, an arc lamp having a housing, a relatively movable end closure pivotally mounted on said housing, positive and negative electrodes in said housing disposed to produce an arc, a reflector supported by the end closure arranged to project light from the arc, means mounted by said housing adapted to support the positive elect-rode, means surrounding the positive electrode provided with orifices arranged to direct a hollow column of air under pressure toward the are for confining the arc, means mounted by said end closure and movable therewith supporting said negative electrode, driving means for each electrode including a first motor mounted by the housing for advancing the positive electrode, a second motor supported by the end closure for advancing the negative electrode, vent means disposed adjacent said negative electrode supported by said end closure, a suction blower supported by said housing, and tubular passages formed in said housing and end closure in communication respectively with said suction blower and said vent means, said tubular passages being arranged for registration when said end closure is in closed position whereby to exhaust the gases of combustion from the arc and the air of the hollow column surrounding the arc.

5. In combination, an arc lamp having a housing provided with a base plate, positive and negative electrodes in said housing disposed to produce an arc, an end closure pivotally connected to the housing, a main reflector supported by the end closure arranged to project light rays from the arc, means mounted on the base plate adapted to support the positive electrode, said supporting means including a pedestal, a head construction substantially surrounding the positive electrode, said head construction including a first pair of separable semi-circular shaped members arranged in mating relation about the axis of the positive electrode, said members being formed with semi-spherically shaped curved reflecting surfaces arranged to reflect light through the arc toward the main reflector, a second pair of separable semicircular shaped members surrounded by said first pair of semicircular shaped members formed with air passages arranged to deliver a plurality of air streams substantially surrounding the arc, a third pair of semicircular shaped members disposed adjacent said first and second pairs of members, each member of said third pair being formed with a channel arranged to accommodate a circulating cooling liquid, and means 'for conducting current to said electrodes.

6. In combination, an arc lamp having a housing, an end closure pivotally mounted by the housing, positive and negative electrodes in said housing disposed to produce an arc, means supporting each of said electrodes, means individual to each electrode for advancing same including a variable speed driving motor for each electrode, the driving motor for the positive electrode being mounted by the housing, the driving motor for the negative electrode being mounted by the end closure, a curved reflector mounted by the end closure arranged to project light rays from the arc, a current supply circuit for said electrodes, a first relay connected with a current conductor for the negative electrode rendered operable by current variations in said conductor, manually operable rheostat means in the circuit of the motor for the positive electrode for changing the speed of the motor for advancing the positive electrode and simultaneously changing the current flow in said current conductor, a light energy responsive current-producing means in said housing reflector means for directing a beam of light from the arc onto the light energy responsive means amplifying means for amplifying the current produced by said light energy responsive means, a second relay means being in circuit the light energy responsive means with and influenced by the amplified current from said light energy responsive means whereby variations in the current produced by the light energy responsive means actuates said second relay means to change the speed of the motor for advancing the positive electrode, a third relay means in circuit with the first relay means, resistance means associated with said third relay means for changing the speed of the motor for advancing the negative electrode, said third relay being rendered operable by actuation of said first relay.

7. In combination, an arc lamp having a housing, an end closure pivotally supported on the housing, positive and negative electrodes disposed in the housing and arranged to produce an arc, a current supply circuit for said arc, a first motor mounted by the housing arranged to advance the positive electrode, a second motor mounted by the end closure arranged to advance the negative electrode, an arc current selector rheostat for varying the current in the arc circuit, a positive electrode [feed rheostat in circuit with the positive electrode feed motor for varying the speed thereof, means intercalated with the arc current selector rheostat for varying the speed of the negative electrode feed motor, said arc current selector rheostat and said positive electrode feed rheostat being mechanically connected, and manually operable means connected with said mechanical connecting means of said rheostats for simultaneously actuating both said rheostats.

References Cited in the file of this patent UNITED STATES PATENTS 280,426 Wheeler July 3, 1883 707,982 Taylor Aug. 26, 1902 964,664 Little July 19, 1910 1,235,272 Wohl July 31, 1917 1,576,572 Chandeysson Mar. 16, 1926 1,631,529 Hill June 7, 1927 1,681, 153 Johnston Aug. 14, 1928 1,731,104 Mayer Oct. 8, 1929 1,795,169 Hill Mar. 3, 1931 1,937,379 Berg Nov. 28, 1933 1,991,744 Hall Feb. 19, 1935 2,065,735 Peddey Dec. 24, 1936 2,097,767 McAuley et al Nov. 2, 1937 2,107,148 Gretener Feb. 1, 1938 2,160,490 Strong May 30, 1939 2,291,947 Buchwald Aug. 4, 1942 2,396,436 Richardson Mar. 12, 1946 2,401,722 Clapp et al. June 11, 1946 4,957 Zimmerman Nov. 30, 1948 2,540,256 Gretener Feb. 6, 1951 2,569,917 Bergmann Oct. 2, 1951 2,622,224 Hatch Dec. 16, 1952 2,656,482 Hatch Oct. 30, 1953 2,663,792 Gretener Dec. 22, 1953 2,785,333 Hatch Mar. 12, 1957 2,788,459 Gretener Apr. 9, 1957 FOREIGN PATENTS 576,393 Great Britain Apr. 2, 1946 994.221 France Aug. 3, 1951 

1. IN COMBINATION, AN ARC LAMP HAVING A HOUSING, A PAIR OF ELECTRODES IN SAID HOUSING DISPOSED TO PRODUCE AN ARC, AN END CLOSURE PIVOTALLY CONNECTED WITH SAID HOUSING, A REFLECTOR PROVIDED BY THE END CLOSURE ARRANGED TO PROJECT LIGHT RAYS FROM THE ARC, AN ANNULAR MEMBER SUPPORTING SAID REFLECTOR, MEANS ASSOCIATED WITH SAID END CLOSURE SUPPORTING SAID ANNULAR MEMBER, SAID ANNULAR MEMBER BEING FORMED WITH CIRCUMFERENTIALLY SPACED CAM SURFACES, A PLURALITY OF ELEMENTS MOUNTED BY THE PIVOTED END CLOSURE AND SPACED CIRCUMFERENTIALLY ADJACENT SAID CAM SURFACES, A MEMBER ENGAGING EACH OF SAID ELEMENTS, CAM FOLLOWERS CARRIED BY SAID ELEMENTS AND ENGAGEABLE RESPECTIVELY WITH SAID CAM SURFACES, MEANS SUPPORTED ON SAID END CLOSURE ACCESSIBLE EXTERIORLY OF THE CLOSURE FOR MOVING SAID MEMBERS AND ELEMENTS SIMULTANEOUSLY FOR ADJUSTING SAID REFLECTOR LENGTHWISE OF ITS AXIS, AND MANIPULATING MEANS INDIVIDUAL TO CERTAIN OF SAID ELEMENTS FOR SELECTIVELY MOVING SAID ELEMENTS WHEREBY CERTAIN OF 